__ are compounds of formula R-O-R', where R and R' may be __ or __. Like alcohols, __ are related to water with __ replacing the H atoms. In alcohol, one hydrogen atom of water is replaced by an __. In an __, both hydrogens are replaced by alkyl groups. The two alkyl groups are the same in a __ and different in an __.

ethers

alkyl groups or aryl (benzene ring) groups

ethers

alkyl groups

ether

alkyl groups x2

symmetrical ether

unsymmetrical ether

Ethers are relatively __, however, and they are not frequently used as __. Because they are stable with many types of reagents, ethers are commonly used as __ for organic reactions.

The most important commercial ether is __, often called __ or simply __, which is a good solvent for reactions and extractions, and it is used as a __ for diesel and gasoline engines.

unreactive

synthetic intermediates

solvents

diethyl ether

ethyl ether

ether

volatile starting fluid

Like water, ethers have a __, with an __ hybrid oxygen atom giving a nearly __ bond angle. In wter, the nonbonding electrons compress the H-O-H bond angle to __, but in a typical ether, the bulk of the alkyl group does what to the bond angle.

Although ethers lack the __, they are still strongly polar compounds. The __ of an ether is the vector sum of two polar C-O bonds, with a substantial contribution from the two lone pairs of electrons. An ether such as __ provides a strongly __ without the reactivity of a __.

bent structure

sp3

tetrahedral bond angle

104.5

enlarges the bond angle

polar hydroxyl group of alcohols

dipole moment

THF

polar solvent

hydroxyl group

The BP of dimethyl ether and diethyl ether are what compared to alcohols having similar molecular weights?
This large difference results from what?
Pure ethers cannot do what because they have no __. Ethers do have __, resulting in __ but these attractions appear to have relatively little effect on their __.

nearly 100 degrees Celsius lower

hydrogen bonding of alcohols

hydrogen bonding

O-H groups

dipole moments

dipole-dipole attractions

BPs

Although pure ethers have no __ to engage in __, they can __ with other compounds that do have __ or __ groups. A hydrogen bond requires both a __ and a __. The __ is the molecule with an O-H or N-H group. The __ is the molecule whose lone pair of electrons forms a weak partial bond to the hydrogen atom provided by the __. An ether molecule has the lone pair to form a hydrogen bond with an alcohol, but it cannot do what? As a result, ethres are much more __ than alcohols having similar MWs.

hydroxyl groups

hydrogen bonding

hydrogen bond

O-H

N-H

hydrogen bond donor

hydrogen bond acceptor

donor

acceptor

donor

form a hydogen bond with another ether molecule

volatile

Ehters are ideally suited as __ for many organic reactions. They dissolve a wide range of __ and __ substances, and their relatively low __ simplify their __ from the reaction products. __ tend to be more soluble in ethers than in alcohols because ethers have no __to be broken up by the __.

solvents

polar and nonpolar

BPs

evaporation

Nonpolar substances

hydrogen-bonding network

nonpolar solute

Polar substances tend to be nearly as soluble in ethers as in alcohols because ethers have __ as well as the ability to serve as __. The __of an ether effectively __. Ethers do not solvate __as well as alcohols do, however. Ionic substances with __ requiring strong __to overcome their __ are often insoluble in ether solvents. Substances with __, such as iodides, acetates, and other organic anions, tend to be more soluble in ether solvents than substances with __ such as fluorides.

large dipole moments

hydrogen bond acceptors

nonbonding electron pairs

solvate cations

anions

small, "hard" anions

solvation

ionic bonding

large, diffuse anions

smaller, harder anions

Alcohols cannot be used as __ for reagents that are more strongly __ than an __. The __ quickly __ the base, destroying the basic reagent.

Ethers are __ and they are normally unreactive toward __. For this reason, ethers are frequently used as solvents for __ that require polar solvents.

solvents

basic

alkoxide ion

hydroxyl group

nonhydroxylic (no hydroxyl group)

strong bases

very strong polar bases (like the Grignard reagent)

The special properties of ethers (__, __, but relatively __) enhance the formation and use of many reagents. For example, __ cannot form unless an ether is present, possibly to share its __ with the Mg atom. This __ stabilizes the reagent and helps keep it in solution.

An ether's nonbonding electrons also stabilize __. Pure __ exists as a dimer called __. __ is toxic, flammable, and explosive gas, whose use is both dangerous and inconvenient. Borane forms a stable complex with __. The __ complex is commercially available as a 1 M solution, easily measured and transferred like any other air sensitive liquid reagent. The availability of __ has contributed greatly to the convenience of __.

polarity

lone pairs

unreactive

Grignard reagents

lone pairs of electrons

sharing of electrons

borane, BH3

borane

diborane

B2H6

diborane

tetrahydrofuran

BH3⋅THF x2

hydroboration

__ is used as a __ in a wide variety of reactions. Like diborane, __ is a toxic gas, but it forms a stable complex with ethers, allowing it to be conventiently stored and measured. The complex of __ with diethyl ether is called __.

__ are large cyclic polyethers that specificalyl solvate metal cations by complexing the metal in the center of the ring. Different __ solvate different cations, depending on teh relative sizes of the __ and the cation and the number of __ around the cation. The __ of __ shows that the cavity in the center of the molecule is surrounded by electron-rich oxygen atoms that complex with the __.

boron trifluoride

Lewis acid catalyst

BF3 x2

diethyl ethre

borno trifluoride etherate

crown ethers x3

binding sites

EPM

18-crown-6

guest potassium cation

__by __ often helps polar inorganic salts to dissolve in nonpolar organic solvents. This enhanced solubility alows __ to be used under __, where the __ may show greatly enhanced reactivity. Many other salt can be dissolved in __ (and often __) organic solvents using __. In each case the __ complexes only the cation, leaving the anion bare and highly reactive.

complexation

crown ethers

ppolar salts

aprotic conditions

complexed anions

aprotic

nonpolar

crown ethers

crown ether

How are common names of ethers formed?
They should be named how but are frequently named how?

If both groups are the same, lets say methyl, the name is __. If just one alkyl group is described in the name, it implies what?

by naming the two alkyl groups on oxygen and adding the word ether

in alphabetical order

in order of increasing complexity

dimethyl ether

the ether is symmetrical, as in ethyl ether

IUPAC use the __ as the root name, and the rest of the ether as an __.

Cyclic ethers are our first examples of __, containing a ring in which a ring atom is an element other than carbon. This atom, called hte __, is numbered one in numbering the ring atoms. __ are especially and useful ethers.

alkyl group

alkoxy group

heterocyclic compounds

heteroatom

heterocyclic ethers

__ are three membered cyclic ethers, usually formed by __ of the corresponding alkenes. The common name of an __ is formed by adding __ to the name of the alkene that is oxidized. One systematic method for naming epoxides is to name the rest of the molecule and use the term __ as a substituent, giving the numbers of the two carbon atoms bonded to the __.

epoxides

peroxyacid oxidation

epoxide

oxide

epoxy

epoxide oxygen

Another systematic method names __ as derivatives of the parent compound, __, using __ as the systematic name for __. In this system, the ring atoms of a heterocyclic compound are numbered starting with what and going in the direction giving what.

epoxides

ethylene oxide

oxirane

ethylene oxide

the heteroatom

the lowest substituent numbers

The lease common cyclic ethers are the four-membered __. Because tehse four-membered rings are __, they are more reactive than larger cyclic ethers and open-chain ethers. They are not as reactive as the highly strained __, however.

The five-membered cyclic ethers are commonly named after an aromatic member of this group, __. The systematic term __ is also used for a five-membered ring containing an oxygen atom.

oxetanes

strained

oxiranes (epoxides)

furan

oxolane

The saturated five-membered cyclic ether resembles __ but has four additional hydrogen atoms. Therefore, it is called __. One of the most polar ethers, __ is an excellent nonhydroxylic organic solvent for polar reagents. __ sometimes succeed in __even when they fail in __.

furan

tetrahydrofuran (THF) x2

Grignard reactions

THF

diethyl ether

The six-membered cyclic ethers are commonly named as derivatives of __, an unsaturated ether. The saturated compound has four more hydrogen atoms, so it is called __. The systematic term __ is also used for a six-membered ring containing an oxygen atom.

Heterocyclic ethers with two oxygen atoms in a six-membered ring are called __. The most common form of __ is the one with the two oxygen atoms in a 1,4-Dioxane is miscible with water and it is widely used as a polar solvent for organic reactions.

pyran

tetrahydropyran (THP)

oxane

dioxanes

dioxane

__ is a common name for dibenzo-1,4-dioxane, which is __ fused with __. Most __ are toxic and carcinogenic because they associate with DNA and cause a misreading of the genetic code.

dioxin

1,4 dioxane

two benzene rings

dioxins

__ do not show obvious or reliable absorptions for ethers. Most ethers give a moderate to strong C-O stretch around __ (in the __ region), but many compounds other than ethers give similar absorptions. Nevertheless, the __ can be useful because it shows the absence of __ and __ groups. If the molecular formula contains an oxygen atom, the lack of __ or __ absorptions in the IR suggests an ether.

infrared spectra

1000 to 1200 cm^-1

fingerprint

IR spectrum

carbonyl (C=O)

hydroxyl (O-H)

carbonyl

hydroxyl

The most common fragmentation of ethers is what?

Because this carbon is __ to the oxygen atom, this fragmentaiton is caleld __. The resulting __ is resonance stabilized by the nonbonding electrons on oxygen.

Another common cleavage is what?

cleavage next to one of the carbon atoms bonded to oxygen

alpha

alpha cleavage

oxanium ion (oxygen with three bonds and a positive charge)

loss of either of the two alkyl groups to give another oxonium ion or an alkyl cation

The four most abundant ions correspond to the __, __, __, and __. All these modes of cleavage form __.

molecualr ion

loss of an ethyl group

alpha cleavage

loss of an ethylene molecule combined with alpha cleavage

resonance-stabilized oxonium ions

In the 13 C __, a carbon atom bonded to oxygen generally absorbs between δ 3.5 and δ 4 in the 1H __. Both alcohols and ethers have __ in this range.

NMR spectrum

NMR spectrum

resonances

The __ is the most reliable and versatile ther synthesis. This method involves the __ of an __ on an unhindered __ or __. Secondary __ and __ are occasionally used in the __, but __ competes and the __ are often poor.

The __ is commonly made by adding Na, K, or NaH to the __.

Williamson ether synthesis

Sn2 attack

alkoxide ion

primary alkyl halide

tosylate

alkyl halides

tosylates

Williamson synthesis

elimination

yields

alkoxide

alcohol

A __ can be used as an __, but not the halide fragment, for the __. __ are more __ than __ and __ is sufficiently __ to form the __ ion. As with other alkoxides, the __ should have an __ and a good __.

phenol (aromatic alcohol)

alkoxide fragment

Williamson ether synthesis

phenols

acidic

aliphatic alcohols

sodium hydroxide

basic

phenoxide

electrophile

unhindered primary alkyl group

leaving group

The __ process adds a molecule of an alcohol across the double bond of an alkene. The product is an __.